In offshore drilling and production operations, equipment are often subjected to harsh conditions thousands of feet under the sea surface with working temperatures of −50° F. to 350° F. with pressures of up to 15,000 psi. Subsea control and monitoring equipment commonly are used in connection with operations concerning the flow of fluid, typically oil or gas, out of a well. Flow lines are connected between subsea wells and production facilities, such as a floating platform or a storage ship or barge. Subsea equipment include sensors and monitoring devices (such as pressure, temperature, corrosion, erosion, sand detection, flow rate, flow composition, valve and choke position feedback), and additional connection points for devices such as down hole pressure and temperature transducers. A typical control system monitors, measures, and responds based on sensor inputs and outputs control signals to control subsea devices. For example, a control system attached to a subsea tree controls down-hole safety valves. Functional and operational requirements of subsea equipment have become increasingly complex along with the sensing and monitoring equipment and control systems used to insure proper operation.
To connect the numerous and various sensing, monitoring and control equipment necessary to operate subsea equipment, harsh-environment connectors are used with electrical cables, optical fiber cables, or hybrid electro-optical cables. Initial demand for subsea connector development was in connection with military applications. Over time demand for such connectors has grown in connection with offshore oil industry applications. There exists a variety of wet-mate and dry-mate electrical and optical connectors that may be employed in subsea communication systems. In some known underwater electrical connectors, such as that described in U.S. Pat. Nos. 4,795,359 and 5,194,012 of Cairns, which are incorporated herein by reference in their entirety, tubular socket contacts are provided in the receptacle unit, and spring-biased pistons are urged into sealing engagement with the open ends of the socket assemblies. Examples of prior pressure compensated wet-mate devices are described in U.S. Pat. Nos. 4,616,900; 4,682,848; 5,838,857; 6,315,461; 6,736,545; and 7,695,301, each of which is incorporated by reference herein in their entirety. U.S. Pat. No. 4,666,242 of Cairns, which is incorporated herein by reference in its entirety, describes an underwater electro-optical connector in which the male and female connector units are both oil filled and pressure balanced. Other known seal mechanisms involve some type of rotating seal element along with an actuator for rotating the seal element between a closed, sealed position when the units are unmated, and an open position when the units are mated, allowing the contact probes to pass through the seal elements into the contact chambers. Such connectors are described, for example, in U.S. Pat. Nos. 5,685,727 and 5,738,535 of Cairns, which are incorporated by reference herein in their entirety.
To facilitate communication between these underwater devices, and between different communication mediums and network types, systems and control device are employed to manage the subsea equipment. Subsea communication may be implemented by fiber optic, electrical, or hybrid optical-electric communication systems. Fiber optic communication systems typically employ one or more optical fibers, while electrical communication systems employ copper wire which may be implemented as a twisted pair. Communication between devices and pieces of equipment may be on a TCP/IP network and may be handled by one or more modems, switches, routers, and control apparatuses. In a typical subsea communication network having a plurality of wellheads a large subsea router module, such as those manufactured by FMC Technologies or General Electric Oil & Gas, is employed to manage and facilitate communications between one or more subsea devices and other equipment on the surface. For example, an oil platform may have an umbilical that connects equipment on the surface at the oil platform to subsea equipment and that terminates at an umbilical termination head. The umbilical termination head will then have one or more leads that connect data lines from the umbilical to a subsea router module. The large subsea router module then facilitates communication between the surface and other subsea equipment such as wellheads, distribution units, and monitoring equipment. The subsea routing module, in some implementations, may also be configured to transform or convert signals from one form to another to facilitate communications between a plurality of subsea devices. For example, the subsea router module may be configured to convert optical input signals into electrical output signals or convert electrical input signals into optical output signals.
The primary issue with subsea router modules is that the modules are large and expensive. Additionally, even though the modules may provide a form of internal redundancy for subsea device connections, these modules are prone to single points of failure from loss of power, pressure loss, or leaks. For example, a subsea router module may have 3 redundant systems for communicating with a set of wellheads, but if the atmospheric chamber in which the systems are located experiences a leak or pressure failure, all of the redundant systems will fail simultaneously. Furthermore, installing a subsea router module is time consuming and expensive. The subsea router module is a large piece of equipment that must be lowered to the sea floor by a crane or similar apparatus suitable for installing large, heavy equipment. The router module is also difficult to service and maintain once it has been installed subsea. The difficulties in installing and maintaining a subsea router module cause the subsea router module to be a costly piece of equipment to implement.
The subsea router module is also not particularly well suited to every type of subsea equipment configuration. The subsea router module may offer some advantages when used with a larger number, e.g. eight or more, wellheads or wellhead trees that are spaced large distances from the umbilical termination head, oil platform, or other surface equipment. However, when a configuration employs a smaller number of wellheads that are in closer physical proximity to the umbilical termination head or surface equipment, the subsea router module is not the ideal choice for routing and subsea communications.
What is needed is a more flexible, redundant, and inexpensive alternative to large subsea router modules. Preferably, the alternative will be able to be installed by a remote operated vehicle (ROV) without the need for a large crane to lower the device to the sea floor. Additionally, the device should be able to manage communications switching and routing in addition to signal conversion. The device should be small and easily movable and replaceable when needed.